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The pharmacokinetics, pharmacodynamics and safety profile of vornorexant were investigated in healthy Japanese participants in three double‐blind studies: a single ascending dose of 1–30 mg (Study 101; n = 6) and multiple ascending doses of 10–30 mg (Study 102; n = 6). Study 202 consisted of two steps: an open‐label, 20 mg repeated‐dose in non‐elderly individuals (Step 1; n = 12) and a double‐blind, 20 mg repeated‐dose in elderly individuals (Step 2; n = 8/3 for vornorexant/placebo). Vornorexant was rapidly absorbed and eliminated under fasting conditions, with a time to maximum plasma concentration of 0.500–3.00 h (range) and elimination half‐life of 1.32–3.25 h. The area under the plasma concentration‐time curve (AUC) of vornorexant increased proportionally with dose increments. Sleepiness‐related pharmacodynamic outcome changes (Karolinska sleepiness scale, digit symbol substitution test and psychomotor vigilance task) were generally increased with dose increments at 1 and 4 h post‐dose, whereas no consistent dose‐related changes were detected the next morning. Food intake did not affect the maximum observed plasma concentration of vornorexant but increased the AUC0–inf. Exposure in elderly individuals was generally comparable to that in non‐elderly individuals. Altogether, vornorexant may have a favourable profile for insomnia treatment, including rapid onset of action and minimal next‐day residual effects. [ABSTRACT FROM AUTHOR]

We evaluated the in vitro drug–drug interaction (DDI) potential of enerisant (TS-091), a histamine H3 receptor antagonist/inverse agonist, mediated by cytochrome P450 (CYP) and transporters, as well as the pharmacokinetics of enerisant in healthy male subjects. Enerisant did not inhibit CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, or CYP3A4 and did not induce CYP1A2, CYP2B6, or CYP3A4. Enerisant inhibited organic cation transporter 2, multidrug and toxin extrusion protein (MATE) 1, and MATE2-K, but not P-glycoprotein (P-gp), breast cancer resistance protein, organic anion transporting polypeptide (OATP) 1B1, OATP1B3, organic anion transporter (OAT) 1, or OAT3. Enerisant was a substrate for P-gp, but not for eight other transporters. In healthy male subjects, enerisant was rapidly absorbed after oral administration, and the plasma concentration increased dose-dependently. The urinary excretion of enerisant within 48 h after administration was 64.5% to 89.9% of the dose, indicating that most of the absorbed enerisant was excreted in the urine without being metabolized. Based on the plasma concentrations at the estimated clinical dose, enerisant is unlikely to cause CYP-mediated, clinically relevant DDI. Although the possibility of transporter-mediated, clinically relevant DDI cannot be ruled out, there is little or no risk of side effects. [ABSTRACT FROM AUTHOR]

The purpose of this study was to predict the drug-drug interactions ( DDIs) via CYP3A4 by estimating the extent of hepatic CYP3A4 inhibition based on a physiologically based pharmacokinetic ( PBPK) model of both substrate and inhibitor and the increase in the intestinal availability ( Fg) due to the enzyme inhibition. For the DDIs resulting from reversible inhibition of CYP3A4, the prediction using in vivo Ki values estimated from other clinical DDI studies and predicted in vivo Ki values calculated using the correlation between the log P and the in vivo Ki/ in vitro Ki ratio was more accurate than that using in vitro Ki values. Incorporating inhibition of both intestinal and hepatic metabolism resulted in better prediction than that obtained considering inhibition in the liver alone, and all the DDIs ( AUC increase by the inhibitor) were predicted within 2-fold accuracy when in vivo Ki values were used. In addition, Fg values were successfully back-calculated from the clinical DDI data based on the present model. In conclusion, the present PBPK model incorporating the in vivo Ki values was found to be useful for quantitative prediction of clinical DDIs and for estimation of the Fg values for CYP3A4 substrates for which intravenous data were not available. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3183-3193, 2015 [ABSTRACT FROM AUTHOR]